1. Field of the Invention
The present invention relates to an internal combustion engine controller for controlling timing of fuel injection, ignition, etc., with respect to each of a plurality of cylinders of an internal combustion engine on the basis of a reference position signal and a cylinder discrimination signal and, more particularly, to a cylinder identifying apparatus for an internal combustion engine capable of detecting in a short time a reference position of each of cylinders in a multicylinder internal combustion engine.
2. Description of the Related Art
In general, in the internal combustion engines for motor vehicles, etc., there is a need to control and optimize fuel injection, ignition timing, etc., according to operating conditions. Therefore, signal generation means including sensors are provided on rotational shafts of the internal combustion engine to obtain a reference position signal indicating a reference crank angle position of each cylinder and a cylinder discrimination signal for discrimination of each cylinder. Cylinder identification is performed on the basis of those signals.
For example, a conventional cylinder identifying apparatus for an internal combustion engine such as the one disclosed in Japanese Patent Laid-Open No. 6-146992 sets a reference crank angle position with respect to each of predetermined rotation angles; places a cylinder discrimination signal so that the number of generated pulses of the cylinder discrimination signal varies with respect to consecutive intervals of a crank angle position signal; and performs cylinder identification from a combination of pulses of the cylinder discrimination signal generated during consecutive two time periods.
Another conventional cylinder identifying apparatus for an internal combustion engine such as the one disclosed in Japanese Patent Laid-Open No. 11-311146 divides the above-mentioned signal interval into a plurality of time periods starting from a reference crank angle position signal, and performs cylinder identification from a combination of pulses of a cylinder discrimination signal generated during the plurality of time periods.
In the above-mentioned conventional cylinder identifying apparatuses for the internal combustion engines, cylinder identification is performed on the basis of combinations of pulses of the cylinder discrimination signal in the plurality of time periods starting from the reference crank angle position. Therefore it is necessary to detect a plurality of the reference crank angle positions before completing cylinder identification.
Also, since cylinder identification is performed only by the cylinder discrimination signal, if the discrimination signal is formed as different forms related to cylinders, the cylinder discrimination signal becomes so complicated that the cost for identification is disadvantageously high.
In view of the above-mentioned problem with the conventional art, an object of the present invention is to provide a cylinder identifying apparatus for an internal combustion engine capable of reducing the engine rotation angle required for cylinder identification at the time of startup and capable of reducing the startup time.
According to the present invention, there is provided a cylinder identifying apparatus for an internal combustion engine, including: cylinder discrimination signal generation means for generating a cylinder discrimination signal in correspondence with each of cylinders of the internal combustion engine according to the rotation of a camshaft of the internal combustion engine; and crank angle position signal generation means including a member rotating through two revolutions when the camshaft rotates through one revolution, the crank angle position signal generation means for generating a crank angle position signal including pulse dropout portions corresponding to each of the cylinders of the internal combustion engine in accordance with the rotation angle of a crankshaft of the internal combustion engine.
Further, the cylinder identifying apparatus for an internal combustion engine according to the present invention includes a control unit for detecting the crank angle position signal to obtain the number of detections of the crank angle position signal; detecting a reference crank position on the basis of one of the pulse dropout portions of the crank angle position signal; detecting the cylinder discrimination signal to obtain the number of detections of the cylinder discrimination signal; obtaining the number of detections of the crank angle position signal when the cylinder discrimination signal is detected; obtaining the number of pulse dropouts on the basis of one of the pulse dropout portions of the crank angle position signal; obtaining the number of detections of the reference crank position; and setting a first cylinder discrimination period with reference to the reference crank position when the control unit determines that the present reference crank position is the result of first-time detection after startup on the basis of the number of detections of the reference crank position.
Also, the cylinder identifying apparatus includes the control unit for setting a second cylinder discrimination period different from the first cylinder discrimination period with reference to the reference crank position when the control unit determines that the present reference crank position is the result of second-time or some other subsequent detection after the startup; obtaining the number of detections of the cylinder discrimination signal in the first or second cylinder discrimination period on the basis of the number of detections of the cylinder discrimination signal and the number of detections of the crank angle position signal at the time of detection of the cylinder discrimination signal; and identifying one of the cylinders on the basis of the number of pulse dropouts and the number of detections of the cylinder discrimination signal in the first or second cylinder discrimination period.
As a result, the crank angle required for cylinder identification may be reduced, and such an effect can be obtained that the startup time at the time of startup may be reduced.
According to the present invention, there is provided a cylinder identifying apparatus for an internal combustion engine, including: cylinder discrimination signal generation means for generating a cylinder discrimination signal in correspondence with each of cylinders of the internal combustion engine according to the rotation of a camshaft of the internal combustion engine; and crank angle position signal generation means including a member rotating through two revolutions when the camshaft rotates through one revolution, the crank angle position signal generation means for generating a crank angle position signal including pulse dropout portions corresponding to each of the cylinders of the internal combustion engine in accordance with the rotation angle of a crankshaft of the internal combustion engine.
Further, the cylinder identifying apparatus for an internal combustion engine according to the present invention includes a control unit for detecting the crank angle position signal to obtain the number of detections of the crank angle position signal; detecting a reference crank position on the basis of one of the pulse dropout portions of the crank angle position signal; detecting the cylinder discrimination signal to obtain the number of detections of the cylinder discrimination signal; obtaining the number of detections of the crank angle position signal when the cylinder discrimination signal is detected; obtaining the number of pulse dropouts on the basis of one of the pulse dropout portions of the crank angle position signal; setting a temporary cylinder discrimination period with reference to the reference crank position; and obtaining the number of detections of the cylinder discrimination signal in the temporary cylinder discrimination period on the basis of the number of detections of the cylinder discrimination signal and the number of detections of the crank angle position signal at the time of detection of the cylinder discrimination signal.
Also, the cylinder identifying apparatus includes the control unit for setting the present crank position as a selected reference crank position when the cylinder discrimination signal is detected in the temporary cylinder discrimination period; setting a cylinder discrimination period with reference to the selected reference crank position; obtaining the number of detections of the cylinder discrimination signal in the cylinder discrimination period on the basis of the number of detections of the cylinder discrimination signal and the number of detections of the crank angle position signal at the time of detection of the cylinder discrimination signal; and identifying one of the cylinders on the basis of the number of pulse dropouts and the number of detections of the cylinder discrimination signal in the cylinder discrimination period.
As a result, the crank angle required for cylinder identification may be reduced, and such an effect can be obtained that the startup time at the time of startup may be reduced.